Would be maningful to have instead just a fan, maybe SMBus controlled, to smoothly working only when needed? I wonder if exist something, like a rig to mount when I need to use 4K60p or the like. Because I think is cool to see the SoC package naked , specially when a heatsink is not always needed. Not that I see other reasons, unless application dependent.

Does exist something like that, or the reason why I don't find it is because no one would use it?

I'm planning to setup a NAS/NextCloud/VPN server with my 4, when I've got everything on I'll see what load I'm getting and make the choice then. I would think the heatskink will suffice to be honest, save the fan for a desktop.

I used a PoE HAT with fan and it kept the Pi4 very cool indeed. 50-55. Without, a good 15-25 higher depending on load. This is with no case.

With no case, I am not convinced the Pi4 needs any extra cooling at all (in the UK at least).
While it idles at around 50C which seems a lot, it happily runs really large jobs, maxing out all four cores for long periods, without reaching throttling. I could only get it to throttle with a silly artificial stress test.
I upped the clock to 1.6GHz and it remains stable without throttling.
I am surprised (and pleased!).

That's assuming "vcgencmd get_throttled" is reporting correctly.

The Pi4 is mounted on edge in free air.

Like the 3B+, it has considerable thermal inertia, but the Pi4 is much faster so that larger jobs will complete before the temp rises much.

With no case, I am not convinced the Pi4 needs any extra cooling at all (in the UK at least).

Even better is to get aluminum case - it is both big heatsink and case. Especially with the 3B+ model the heat goes to the board itself so it is nicely transferred to the case (unlike with older 3B model where this is not so efficient). There are cheap ones for Pi3 on ebay (like this one) however they will need redesign for Pi4.

I have one and it gets nicely warm so it works. Some may partly block wifi signal, this one has more parts so the part near wifi can be left out.

Last edited by fanoush on Thu Jun 27, 2019 8:07 am, edited 1 time in total.

Indeed. With 3B+ I use as a desktop I moved to wired ethernet too as I have it near. Also I play streamed games over Steam Link occasionally and the wireless in Pi3 has some performance issues documented here - it works fine but slows down every few (5, 10?) minutes killing frame rate => game over.

Anyway what I wanted to say is that the question should not be "heatsink or fan" because the correct answer may be "neither, get aluminium case".

In order to cool the CPU, you need to move the heat it generates away as quickly and efficiently as possible.
Adding a heatsink with good thermal contact with the CPU will allow the heat to transfer quickly into the heatsink. But there will come a point at which even the thermal capacity of the heat sink becomes saturated, at which point it will stop being as effective, the CPU will heat up and start throttling. The heat sink provides a greater surface area from which the heat can radiate/convect, so this does help, but essentially, it is just delaying the time until throttling occurs.
For light use, this increased passive cooling may be sufficient, especially if the CPU is mostly idle but is occasionally used for bursts of activity.
Of course, making the heatsink bigger extends the time further and allows the cooling to be more effective due to the larger surface area. So using a whole case as a heatsink is a good idea. In many cases (sic) this increased cooling may be sufficient.

For heavier or more sustained use, a more active cooling system like a fan is more advantageous, as it can wick away the heat quite quickly. I tend to find active cooling from a fan is always more effective than a heatsink, but of course it is more costly and uses more power. It may also need to be connected to the GPIO for power/control which may get in the way of other HATs.

For maximum cooling, a heatsink and a fan together is very effective.

So like most things in life it is a compromise and depends on your use case.

My favourite case is the Argon One on my 3B+ as this uses the whole case as a heatsink (with thermal conductivity to the CPU) and includes a fan that adjusts its speed according to the CPU temperature, so it minimises any power and noise. I hope they will make one for the 4B too.

An aluminium case will be of no use unless it is thermally linked to the SOC

Which is the case with 3B+ as understand it (unlike 3B) and possibly also Pi4 (sea also this and linked blogs). They explained it somewhere that the SOC is upside down in 3B+ and heat goes into board ground plane, metal connectors (USB, ethernet,..) and thus also the case. So the case may be much better than isolated heatsink on top of CPU.

Last edited by fanoush on Thu Jun 27, 2019 11:42 am, edited 1 time in total.

The metal can around the 3B+ and 4B CPU is a pretty good thermal conductor. You just need different thicknesses of thermal tape to account for the different heights for the processor to contact the case (In the ArgonOne case for the 3B/3B+ anyway, I assume similar for FLIRC).

The heat sink provides a greater surface area from which the heat can radiate/convect, so this does help, but essentially, it is just delaying the time until throttling occurs.

If the increased heat loss due to convection from the greater surface area (fins) is more than the heat being generated, then it is enough and throttling will not occur.
And that is quite easy to achieve for an ARM based chip.
That is, unless its in an enclosed case with no ventilation, or perhaps in a very hot country.
In the UK, placing a Pi board on edge in free air is often enough, and that seems to be adequate for the Pi4.
Something like this is perhaps an overkill, but your Pi will not throttle ...https://www.kintaro.co/products/kintaro-custom-heatsink
I have used Pi's heavily for years and never needed a fan. They are noisy!
Yes I agree fans are very effective for obvious reasons, but I don't see the need.

My favourite case is the Argon One on my 3B+ as this uses the whole case as a heatsink (with thermal conductivity to the CPU) and includes a fan that adjusts its speed according to the CPU temperature, so it minimises any power and noise. I hope they will make one for the 4B too.

They actually announced (on Facebook) today that they are doing just that, and are already accepting advance orders... at a reduced price of course!